Recipe

Brownie Premix Upgrade Brownies

A boxed mix that bakes up fudgy and shiny-topped, with optional espresso, brown butter, and mix-ins for serious “wait, you made these?” energy.

By Matt Campbell

•

4.8

A metal baking pan filled with fudgy brownies with shiny crackly tops, cut into squares on a warm-toned kitchen counter

Jump to Recipe

Brownie premix is one of my favorite weeknight cheats because it is basically a guaranteed win. But I also refuse to accept sad, one-note brownies when the fix is two tiny upgrades and one very important habit: do not overbake.

This recipe starts with your favorite boxed brownie mix and pushes it into that sweet spot: deep chocolate, crisp edges, and a center that stays plush for days. You can keep it simple, or go slightly chaotic friend-mode and brown the butter, add espresso, and toss in a handful of chopped chocolate. Either way, you are getting brownies worth clearing counter space for.

Boxed brownie mix, eggs, melted butter, cocoa powder, and chocolate chips arranged on a bright kitchen counter

Why It Works

Fudgy texture on purpose: Using melted butter (or browned butter) and an extra yolk makes the crumb richer and less cakey.
Better chocolate flavor: A pinch of espresso powder and a touch of cocoa deepen the mix without making it bitter.
That crackly top: Whisking the wet ingredients until glossy helps create the shiny, papery crust everyone fights over.
Reliable bake: A simple doneness check keeps you out of dry-brownie jail.

Pairs Well With

Storage Tips

How to Store Brownies

Room temp: Store airtight for up to 4 days. For extra fudgy brownies, press a piece of parchment or plastic wrap directly on the cut surface.
Fridge: Up to 7 days airtight. They get denser when chilled, which some people (me) love. Let sit 15 minutes before serving for a softer bite.
Freezer: Wrap squares individually and freeze up to 2 months. Thaw at room temp or warm briefly in the microwave.
Revive: A 10 to 12 second microwave hit makes them taste freshly baked. Add a pinch of flaky salt after warming if you want the full movie-trailer experience.

Common Questions

Can I use butter instead of oil in brownie premix?

Yes, in most mixes. Use the same volume of melted butter as the oil your box calls for (example: if the box says 1/2 cup oil, use 1/2 cup melted butter). If you want to level up, brown the butter, then cool it until it is warm, not hot before mixing so it does not cook the eggs.

How do I make boxed brownies more fudgy?

Three reliable moves: use melted butter, add 1 extra egg yolk, and pull them early. You want moist crumbs on a toothpick, not a clean stick.

What pan size should I use for a typical brownie mix?

Most standard mixes are written for an 8x8-inch or 9x9-inch pan. An 8x8 gives thicker, fudgier brownies. A 9x13 is usually for “family size” mixes. Always check the back of the box, then use the doneness cues in the recipe.

My box says 9x13. Can I bake it in an 8x8 or 9x9 for thicker brownies?

You can, but do it on purpose. A 9x13 mix has more batter, so in an 8x8 or 9x9 it will be much thicker and need more time. Either: (1) use a larger pan as written, or (2) hold back a little batter (bake a few “tester” cupcakes), or (3) bake thicker and plan on a longer bake, checking often and tenting with foil if the top browns too fast.

Why are my brownies dry?

Overbaking is the main culprit. Brownies keep cooking after you pull them. Also, measuring add-ins too aggressively can throw off the batter ratio. If you add lots of chips or nuts, reduce bake time by a few minutes and start checking early.

Can I add mix-ins to brownie premix?

Absolutely. Keep it to about 3/4 to 1 cup total mix-ins so the brownies still set properly. Good picks: chocolate chunks, toasted nuts, crushed pretzels, or swirls of peanut butter.

How do I know when brownies are done?

Look for set edges, a slightly puffed center, and a toothpick that comes out with moist crumbs. If it is clean, you likely went a little too far. If it is wet batter, give it 2 to 3 more minutes.

Matt Campbell

I have always had a huge passion for the culinary arts, people, working as a team, and so on. I wanted to pursue my love for cooking initially at Virginia Commonwealth University with a culinary arts degree; however, I instead decided to apply myself and acquire more practical skills. My end goal is to eventually open my own restaurant or similar establishment.

Kitchen Essentials

8x8-inch or 9x9-inch metal baking pan (metal gives better edges)
Mixing bowl
Whisk and rubber spatula
Measuring cups and spoons
Parchment paper (optional but highly recommended)
Wire rack for cooling

When I decided to chase practical kitchen skills instead of the classroom route, I learned something fast: consistency matters more than perfection. Brownie premix is the same lesson in a box. You can bake it straight and it will still be fine, but once you learn a couple small levers like butter instead of oil, espresso for depth, and pulling the pan before it looks “done” you start getting results that feel like you actually meant to flex.

Brownie Premix Upgrade Brownies

(4.8 Reviews)

Prep Time 10 minutes

Cook Time 25 minutes

Total Time 45 minutes

Servings 12 brownies

Ingredients

1 box brownie premix (usually 18 to 19 oz), plus the ingredients listed on the box
Swap (most mixes): Use melted butter instead of the oil called for (same volume). Example: if the box calls for 1/2 cup oil, use 1/2 cup melted butter.
2 large eggs (or whatever the box calls for)
Optional fudgy boost: 1 extra egg yolk
Optional flavor boost: 1 tsp espresso powder
Optional: 1 tbsp unsweetened cocoa powder
Optional mix-ins: 3/4 cup chocolate chips or chopped chocolate
Optional: Flaky salt for finishing

Note: If your mix calls for water, you can replace it with the same amount of strong coffee for extra chocolate depth.

Instructions

Prep the pan and oven. Heat the oven to the temperature on your box (usually 325°F to 350°F). Line an 8x8-inch or 9x9-inch metal pan with parchment, leaving a little overhang for easy lifting. Lightly butter or spray the parchment.
Melt the butter. Melt the amount of butter that matches the oil listed on the box (example: 1/2 cup oil equals 1/2 cup butter). If you brown it, let it cool until warm and comfortable to the touch before mixing, about 120 to 130°F if you use a thermometer. Hot butter plus eggs equals accidental scrambled situation.
Whisk the wet ingredients for the crackly top. In a mixing bowl, whisk the eggs (and extra yolk if using) for 20 to 30 seconds until a little frothy. While whisking, slowly stream in the warm melted butter to keep things smooth and emulsified. Whisk in the water or coffee your mix calls for. Keep going another 20 to 30 seconds until the mixture looks glossy. This is the part that helps you get that shiny, papery crust without turning the batter into a cement situation.
Add the dry mix and boosts. Sprinkle in the brownie mix (and cocoa powder and espresso powder if using). Switch to a spatula and fold gently just until combined. Stop early. A few tiny streaks are fine because they disappear as you finish folding. The goal is smooth batter, not an arm workout.
Fold in mix-ins. Fold in chocolate chips or chopped chocolate. If you want extra drama, reserve a small handful to scatter on top.
Bake. Scrape batter into the pan and smooth the top. Bake until the edges are set and a toothpick in the center comes out with moist crumbs. Time depends on the mix, pan, and thickness. As a starting point, check at 20 minutes for 8x8 or 9x9, and expect roughly 22 to 30 minutes for many mixes. If you are using a 9x13 pan, the brownies are thinner and can finish sooner, so start checking early and trust the cues more than the clock.
Cool completely, then slice. Let brownies cool in the pan for 20 minutes, then lift out using the parchment and cool fully on a rack before slicing. For clean cuts, chill 30 minutes first, then use a warm knife.
Finish and serve. Sprinkle with flaky salt if you like. Serve as-is, or warm a square and top with vanilla ice cream if you are feeling generous.